For example, a DC-DC converter widely used as an example of a power supply circuit has a configuration in which a high-side power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and a low-side power MOSFET are connected to each other in series. The high-side power MOSFET has a switch function for controlling the DC-DC converter, and the low-side MOSFET has a switch function for synchronizing. These two power MOSFETs are alternately turned on and off while synchronizing, thereby executing a conversion of a power supply voltage.
Such DC-DC converters are described in Japanese Patent Application Laid-Open Publication No. 2003-70247 (Patent Document 1) and NIKKEI ELECTRONICS, Jun. 5, 2006, pp. 138-143 (Non-Patent Document 1), in which the configuration and operation of a circuit generally used in voltage mode control are disclosed.